CONTREX CX-1200 - Manual (Page 311)

8 - 14
ANALOG INPUT TESTS
The Auxiliary Analog tests screens display the input screen (page 1), the output screen (page 2) and the
calibration screen (page 3). The Analog Input screen displays the Monitor Parameters that monitor the
results of inputing a voltage or current. The Analog Output screen displays the Monitor Parameters that
monitor the Auxiliary Analog Output. Use the Aux Analog Calibration screen (page 3) to calibrate the
Auxiliary Analog I/O; AI1, AI2 and AO. The boards is calibrated at the factory and are adequate for most
applications. However, you may need to re-calibrate if your application demands more accuracy in a specific
range or if you need to calibrate directly to EU/Tm with a known signal level on the inputs. The following
sections will explain the calibration for Analog Output (voltage), Analog Output (current), Analog Input 1
(voltage), Analog Input 1 (current), Analog Input 2 (voltage), Analog Input 2 (current), and calibration together
with scaling.
Analog Output (voltage):
1. Connect a voltmeter between pins 10 and 11 with the positive lead on pin 10 (pin 11 is
common).
2. Set AO Mode (CP-291) to “Volts” (1).
3. Set Analog Cal Sel (CP-461) to AO (3) to Select AO for calibration.
4. Set Analog Cal Ref (CP-462) to “A” (1) to select point A.
NOTE: The old calibration data will be overwritten.
5. Set Analog Cal EN (CP-460) to “On” (1) to start calibration.
6. Adjust AO Bit Set (CP-464) until the meter reads the voltage that you want set for point A.
This is generally your smallest (or negative) voltage point. A -12 volts requires about -29500
bits, -10 volts about -24500 bits, 0 volts about 0 bits. For -12 volts, start with about -29400
and use the incremental scroll key .
7. Enter the exact voltage measured by the meter into AnalogRef Val (CP-463).
8. Set Analog Cal Ref (CP-462) to “B” (2) to select point B.
9. Adjust AO Bit Set (CP-464) until the meter reads the voltage that you want use for point B.
This is usually your largest (or positive) voltage point. A +12 volts requires about 30100 bits,
10 volts about 25100 bits, 0 volts about 0 bits. For 12 volts, start with about 30000 and use
the incremental scroll key.
10. Enter the exact voltage measured by the meter into AnalogRef Val (CP-463).
11. Set Analog Cal EN (CP-460) to “Off” (0) to disable further calibration.